High efficiency water heater

摘要

A flue system is provided for a water heater having improved heat exchange efficiency. The flue system includes an upstream heat exchange portion having at least one substantially vertical flue tube. The flue system also includes a downstream heat exchange portion having at least one substantially vertical flue tube. The upstream heat exchange portion provides a first pass for heat exchange with water in a water heater. The downstream heat exchange portion provides a second pass for heat exchange with water in the water heater.